// 算法部分 解决js小数精度问题
function Solution(a, b) {
    //升级
    let a1 = a * 1000;
    let b1 = b * 1000;
    //降级
    let res = a1 * b1 / 1000000;
    return res;
}

console.log(Solution(0.1, 0.09));